He said Labour "currently constitutes" the official opposition and its leader is recognised by the Speaker "for statutory and parliamentary purposes" as the leader of the opposition.

Mr Bercow was replying to a point of order raised by SNP MP Pete Wishart, who told the Speaker that Labour had lost two-thirds of its shadow cabinet and its leader no longer commanded the majority of his backbench MPs.

The SNP MP said: "It can no longer provide shadows for large departments of state. It is clearly in no shape to assume power and meet these key responsibilities and obligations as outlined in Erskine May [the parliamentary rulebook]."

The SNP said it would be able to fill all of the relevant shadow posts to the government.

Mr Corbyn has still not appointed a shadow Scottish secretary.

The previous incumbent, Ian Murray, has not been replaced after becoming one of more than 20 members of Labour's shadow cabinet to quit earlier this week in an effort to force Mr Corbyn to resign.